Electric relay

ABSTRACT

An electric relay including a movable armature wherein the armature includes an electric conducting portion adapted to engage and bridge spaced electrical contacts at a predetermined armature position. During the conducting position of the armature, a mercury applicator mounted on the armature is immersed within a small reservoir of mercury wherein small particles thereof adhere to the applicator upon removal of the armature from engagement with the electrical contacts. Such disengagement of the armature from the contacts positions the applicator adjacent the effective contact surfaces, for random engagement therewith, wherein small mercury particles are transferred to the contact surfaces, to utilize mercury in establishing the electrical circuit between the contacts and the armature electrical conducting portion during subsequent cycles of operation.

United States Patent [111 3,624,567

[72] Inventor Merrill B. Gordon 3,492,532 [/1970 Fayling 335/56 zgf g Cour" wonhlngwn 0M0 Primary Examiner-Harold Broome [2]] App No 21 069 AltorneyBeaman & Beaman [22] Filed Mar. I9, 1970 Patented 1971 ABSTRACT: An electric relay including a movable armature wherein the armature includes an electric conducting portion adapted to engage and bridge spaced electrical contacts at a 1 ELECTRIC RELAY predetermined armature position. During the conducting posi- 8 6 Figs tion of the armature, a mercury applicator mounted on the ar- [52] U.S.Cl. 335/58 m r i immer within a small reservoir of mercury [5 1] Int. Cl "01h 1/08 h e small pa cles the eof adhere to the applicator upon [50] Field of Search 335/581'55, removal of the armature fromengagement with the electrical 56, 57, 80; 200/166 BH contacts. Such disengagement of the armature from the contacts positions the applicator adjacent the effective contact m CIM surfaces, for random engagement therewith, wherein small UNITED STATES PATENTS mercury particles are transferred to the contact surfaces, to

2,129,855 10/1935 MC vaine 335/55 utilize mercury in establishing the electrical circuit between 2,923,792 2/1960 Fry 335/56 the contacts and the armature electrical conducting portion 3,161,745 12/1964 Anderson 335/56 during P' ove'a'o ofois fofo ELECTRIC RELAY BACKGROUND OF THE INVENTION The invention pertains to the field of electric relays wherein conduction through the relay contacts is augmented by the wetting of the contact surfaces with liquid mercury.

It has long been recognized that liquid mercury is of advantage in switches, relays and the like in order to produce an effective and highly dependable electrical connection. Most mercury contact devices either tilt a mercury reservoir wherein the mercury shifts to a position contacting two electrodes to establish a circuit, or the electrodes are moved into engagement with a pool of mercury.

While both of these conventional mercury wetted contact devices produce dependable operation, they require a substantial amount of mercury, and this type of device is usually rather expensive to manufacture. Additionally, the apparatus required with conventional mercury contact devices is usually rather complex, sensitive to orientation and susceptible to damage.

Low-cost relays of conventional manufacture are usually susceptible to failure over a relatively short cycle life, and while the use of mercury in the contacts of relay switches is known to considerably extend the effective life of relay contacts, the cost of mercury, and the complexity of structure usually required with this type of switching device, has not permitted the advantages of a mercury wetted relay to be used in a low cost embodiment.

U.S. Pat. Nos. 2,153,633 and 2,288,811 disclose conventional mercury switching devices and relays which will likely produce dependable operation. However, the amount of mercury required with relays of this type substantially increases the cost of the relay, and also makes the relay operation very susceptible to damage and sensitive to orientation with the horizontal for proper operation.

SUMMARY OF THE INVENTION It is an object of the invention to produce a low-cost relay characterized by its economy of manufacture and dependability of operation wherein the advantages of using liquid mercury at the mutually engaging contacting and conducting surfaces are employed, yet the amount of mercury required is 'very small. Further, the relay of the invention, even though utilizing mercury in its operation, is not as critically sensitive to orientation to the horizontal as most mercury-switching devices, and is capable of dependable operation as long as the relay is mounted in a substantially vertical orientation. Additionally, the relay is so constructed that there is no need to require special handling of the relay during shipping and transportation and is not readily susceptible to damage.

Another object of the invention is to provide a low-cost dependable relay which is suitable for use in automobile lampfilament-monitoring systems which is dependable in operation, rugged in construction, concise in configuration and easy to assemble and replace with respect to the associated circuit.

In the construction of the invention the relay is preferably formed as an encapsulated unit consisting of an electrical coil having a central annature movable between first and second positions depending on whether the coil is energized or deenergized. Preferably, the armature moves to the deenergized position under the influence of gravitational forces. The encapsulated relay body member includes-a pair of spaced contacts located within the path of movement of the armature, which are engaged by the armature at the termination of its movement in one direction, preferably when the coil is in the deenergized state, and the armature is of electrical conducting material so as to bridge the contacts and permit current to fiow therebetween. While the armature is engaging the electrical contacts a probe or applicator mounted upon the armature is immersed within a small mercury reservoir wherein a drop of mercury is located. When the coil is energized to remove the armature from the electrical contacts, small particles of mercury will adhere to the applicator, and when the coil is energized, the applicator is positioned adjacent the contact surfaces. The construction of the armature and its guide, are such that the applicator may randomly engage the contact conducting surfaces and thereby deposit small amounts of mercury upon the contact surfaces. The small particles of mercury will adhere to the contact surfaces and aid in establishing electrical contact between the armature and contacts during the next interengagement therebetween upon deenergizing of the coil.

Preferably, the armature is formed with a convex surface which engages complimentary concave surfaces defined in the electrical contacts, and the combination of these complementary surfaces, wetted with small'mercury particles, produces a most effective electrical path between the contacts and armature. The mercury reservoir is located at the lowermost region of the vertically oriented armature guide, and thus mercury particles falling from the applicator, or the contact surfaces, are received within the mercury reservoir, and the mercury within the relay will always accumulate in the reservoir to effectively cooperate with the applicator.

Preferably, the electrical conductors associated with the relay coil and contacts are in the form of pins extending from a common surface of the enscapsulated relay body, whereby the relay may be plugged" into an associated circuit board. Use of the relay of the invention as an automobile lamp filament monitoring system will necessitate the use of a number of relays with each vehicle, and this plug-in feature of the relay will greatly facilitate initial wiring, and maintenance.

A further object of the invention is to provide a low-cost relay utilizing the advantages of mercury wetted contacts wherein only a small amount of mercury is required, and the mercury within the relay cannot be accidentally lost or accumulate at locations other than that intended.

BRIEF DESCRIPTION OF THE DRAWINGS The aforementioned objects of the invention and the relationships of the components of an embodiment thereof will be appreciated from the following description and accompanying drawing wherein:

FIG. I is an elevational sectional view of a relay constructed in accord with the invention,

FIG. 2 is an elevational sectional view taken along section IlIl of FIG. 1, showing the armature in the lowermost position engaging the contacts,

FIG. 3 is an enlarged, detail, sectional view of the armature, contacts and mercury reservoir,

FIG. 4 is an enlarged, detail, sectional view of the armature and contacts with the armature in the raised position and the applicator engaging a contact surface,

FIG. 5 is a sectional view of the contacts and probe taken along section V-V of FIG. 4, and

FIG. 6 is a detail perspective view of a contact end illustrating the contact surface.

DESCRIPTION OF THE PREFERRED EMBODIMENT The relay of the invention may be utilized in most relay applications well known to those skilled in the art. The disclosed relay embodiment was particularly designed for use with an automobile lamp monitor system wherein a pilot or indicator light is energized should a vehicle lamp filament fail. Lampmonitoring systems of this general type are shown in U.S. Pat. No. 2,127,887, however, in the instant relay the indicator light is to be energized upon failure of the lamp filament, rather than deenergized as in the above-mentioned patent.

As will be appreciated in FIGS. 1 and 2 the relay includes a body member 10, which is preferably of a synthetic plastic material such as urethane or the like, wherein the components of the relay may be completely encapsulated within the material of the body member, and the relay is thereby sealed against the atmosphere. If desired, inert gas may be injected into the relay body member to minimize oxidation.

An annular electric coil 12 is concentrically located within the body member, and pin-type terminals 14 extend from the body member end surface 16, FIG. 1, which are connected to the ends of wire of the electric coil. The electric coil 12 is concentrically located about an armature passage guide 18, and as the disclosed relay is to utilize gravitational forces in its operation, the passage 18 will be referred to as having upper and lower ends, with reference to the drawing.

The upper end of the passage 18 includes an immovable bar core 20 of antiresidual magnetic steel, and of a predetermined length wherein the lower surface 22 functions as a stop for the movable armature, the bar core increases the magnetic force upon the armature during energization of the coil.

A cylindrical armature 24 of mild steel is movably mounted within the passage 18 and has a diameter substantially less than the diameter of the passage as will be apparent in the drawings. Preferably, the upper end 26 of the armature 24 is rounded in order to shed mercury particles that may adhere thereto, and the lower end 28 of the armature includes an elongated mercury applicator pin or probe 30 which extends axially from the lower end of the armature. The applicator 30 preferably has a rather sharp lower end wherein mercury particles adhering thereto will tend to roll to the lowermost region of the applicator and accumulate at the sharpened lower end thereof.

The relationship of the electrical contacts of the relay are best illustrated in FIG. 2, and the electrical contacts include horizontal portions 32 terminating in end portions 34 spaced relative to each other. The vertically extending portions of the contacts constitute pins 36 extending from the body member end surface 16. As will be appreciated in FIG. 6 the contact end portions 34 are each formed with concave surfaces 38, complementary in configuration to the rounded convex lower end 28 of the armature 24 whereby a substantial contact area exists between the lower end of the armature and the contact surfaces 38 when the armature is in the position shown in FIGS. 2 and 3.

The lowermost end of the passage 18 is provided with a conical surface 40 converging toward a smaller recess which constitutes a mercury reservoir 42. A drop of liquid mercury 44 is located within the reservoir 42, as will be appreciated in the drawings, and it will be noted that as the passage 18 is sealed there is no possibility that the mercury can escape from the passage. Should the relay be inverted during transportation and handling, any mercury adhering to the upper end 26 of the armature will shed therefrom due to the rounded con.- figuration thereof, and upon the orienting of the relay in any generally vertical direction, the mercury will accumulate in the reservoir 42.

The length of the armature 24, the location of the core lower surface 22, the length of the liquid mercury applicator 30, and the distance between the mercury reservoir 42 and the contact surfaces 38 are predetermined such that when the coil 12 is energized, the lowermost portion of the applicator 30 will be horizontally aligned with the contact surfaces 38, FIG. 4. Also, the diameter of the armature 24 is substantially less than the diameter of the passage 18 whereby the armature may tilt or wobble within the passage while the coil is energized. Tilting or wobbling of the armature is facilitated by the rounded configuration of its upper end, as well as its lower end.

In operation, the relay will be inserted into a control panel or circuit board, not shown, by means of the coil and contact pins 14 and 36 to establish the desired circuitry. In the aforedescribed use of the relay the coil pins 14 will be placed in the circuit to a vehicle lamp filament, while the pins 36 will be placed in series in the circuit to an indicator lamp located on the dashboard of the vehicle. Energization of the vehicle lamp wiil energize the coil 12, and raise the armature 24 to the position shown in FIG. 4. Thus, as long as the lamp filament is in proper working order, the coil will be energized and the circuit between the contact surfaces 38 is broken. While the armature 24 is in this elevated position the armature will wobble and rock back and forth in the passage 18, causing the applicator end 30 to alternately engage the surfaces 38. As small particles of mercury will adhere to the applicator 30 this random contact of the applicator to the surfaces 38 will deposit small particles of mercury to both contact surfaces, where they will adhere due to frictional and molecular attraction.

Should the vehicle lamp filament fail, the coil 12 will be deenergized, and the armature 24 will fall to its lower position as shown in FIG. 2. In this position, the lower convex end surface 28 will be in engagement with the contact concave surfaces 38, and due to the prior depositing of mercury particles thereon and due to the contact between the armature and the contact surfaces 38 the armature will cause electrical current to flow through the pins 36 and energize the associated indicator light, not shown. The prior deposit of mercury on the surfaces 38 thereby augments the electrical contact between the contacts and the armature 24, and under test conditions a relay constructed in accord with the invention has operated successfully through many hundreds of thousands of cycles. Of course, when the vehicle lamps are deenergized, such as in the daytime, the armature 24 will be in its lowermost position, FIG. 2, where the mercury applicator 30 is immersed in the drop of mercury, and will lift small particles of mercury on its surface as the armature is lifted to the position of FIG. 4 when the lights are energized.

It is appreciated that the relay of the invention may be economically constructed using known manufacturing techniques, and it is merely necessary to place a drop of mercury in the passage 18, and the mercury will automatically accumulate in the reservoir 42. When the armature 24 is in its lowermost position, FIG. 1, the contact surfaces 38 will tend to center and relate the applicator 30 to the drop of mercury to insure immersion therein, and when the coil 12 is energized vibration of the vehicle, and the movement of the annature which will randomly occur during operation of the vehicle insures engagement between the applicator 30 and the contact surfaces 38.

It is appreciated that various modifications to the disclosed embodiment may be apparent to those skilled in the art without departing from the spirit and scope of the invention.

Iclaim:

1. An electric relay characterized by its economy of manufacture and dependability of operation comprising, in combination, a body member, an annular electric coil mounted on said body member, an armature actuated by said coil movable between first and second positions upon energization and deenergization of said coil, an electrical conducting portion defined on said armature, a pair of spaced contacts mounted on said body member each having a contact surface adapted to be engaged by said armature-conducting portion at said first position of said armature, a mercury reservoir defined in said body member, liquid mercury within said reservoir, a mercury applicator mounted on said armature adapted to be immersed within said mercury at said armature first position, said applicator being located adjacent said contact surfaces at said armature second position and engageable with said contact surfaces at said second position to apply particles of mercury to said contact surfaces.

2. An electric relay as in claim I wherein said armature comprises an elongated ferrous element axially movable within a bore defined in said body member circumscribed by said coil, and said electrical conducting portion comprises an end region defined on said element.

3. In an electrical relay as in claim 1 wherein said mercury applicator comprises an elongated probe having a free end, said probe free end being immersed in said mercury at said armature first position and engageable with said contact surfaces at said armature second position.

4. In an electrical relay as in claim 2 wherein said electrical contact surfaces are of a configuration complementary to the configuration of said element end region.

5. In an electrical relay as in claim 4 wherein said element end region is of a convex configuration, and said contact surfaces are each of a concave configuration.

6. In an electrical relay as in claim 1 wherein said body member consists of a synthetic plastic material, an end surface defined on said body member, coil connected pin conductors extending from said body member end surface, and contact connected pin conductors extending from said end surface 7. An electric relay characterized by its economy of manufacture and dependability of operation comprising, in combination, a body member having an elongated vertically oriented passage defined therein having lower and upper ends, an annular electric coil within said body member circumscribing said passage, an elongated ferrous armature axially movable within said passage between said lower and upper ends thereof upon deenergization and energization of said coil, respectively, a pair of spaced electrical contacts mounted on said body member extending into said passage adjacent said lower end thereof each having a contact surface adapted to be engaged by said armature upon said armature being located at said passage lowerend, a mercury reservoir defined at said passage lower end, liquid mercury within said reservoir, a mercury applicator defined on said armature for immersion into said mercury when said armature is located at the lower end of saidpassage, said applicator being disposed adjacent said contact surfaces when said armature is adjacent the upper end of said passage, the transverse cross section of said passage being greater than that of said armature whereby said applicator may engage said contact surfaces during energization of said coil and deposit mercury particles thereon.

8. In an electric relay as in claim 7, a convex surface defined in the lower end of said armature, said contact surfaces being complementarily concave to said convex armature surface and engaged thereby when said armature is adjacent the lower end of said passage.

t t i i 

1. An electric relay characterized by its economy of manufacture and dependability of operation comprising, in combination, a body member, an annular electric coil mounted on said body member, an armature actuated by said coil movable between first and second positions upon energization and deenergization of said coil, an electrical conducting portion defined on said armature, a pair of spaced contacts mounted on said body member each having a contact surface adapted to be engaged by said armature-conducting portion at said first position of said armature, a mercury reservoir defined in said body member, liquid mercury within said reservoir, a mercury applicator mounted on said armature adapted to be immersed within said mercury at said armature first position, said applicator being located adjacent said contact surfaces at said armature second position and engageable with said contact surfaces at said second position to apply particles of mercury to said contact surfaces.
 2. An electric relay as in claim 1 wherein said armature comprises an elongated ferrous element axially movable within a bore defined in said body member circumscribed by said coil, and said electrical conducting portion comprises an end region defined on said element.
 3. In an electrical relay as in claim 1 wherein said mercury applicator comprises an elongated probe having a free end, said probe free end being immersed in said mercury at said armature first position and engageable with said contact surfaces at said armature second position.
 4. In an electrical relay as in claim 2 wherein said electrical contact surfaces are of a configuration complementary to the configuration of said element end region.
 5. In an electrical relay as in claim 4 wherein said element end region is of a convex configuration, and said contact surfaces are each of a concave configuration.
 6. In an electrical relay as in claim 1 wherein said body member consists of a synthetic plastic material, an end surface defined on said body member, coil connected pin conductors extending from said body member end surface, and contact connected pin conductors extending from said end surface.
 7. An electric relay characterized by its economy of manufacture and dependability of operation comprising, in combination, a body member having an elongated vertically oriented passage defined therein having lower and upper ends, an annular electric coil within said body member circumscribing said passage, an elongated ferrous armature axially movable within said passage between said lower and upper ends thereof upon deenergization and energization of said coil, respectively, a pair of spaced electrical contacts mounted on said body member extending into said passage adjacent said lower end thereof each having a contact surface adapted to be engaged by said armature upon said armature being located at said passage lower end, a mercury reservoir defined at said passage lower end, liquid mercury within said reservoir, a mercury applicator defined on said armature for immersion into said mercury when said armature is located at the lower end of said passage, said applicator being disposed adjacent said contact surfaces when said armature is adjacent the upper end of said passage, the transverse cross section of said passage being greater than that of said armature whereby said applicator may engage said contact surfaces during energization of said coil and deposit mercury particles thereon.
 8. In an electric relay as in claim 7, a convex surface defined in the lower end of said armature, said contact surfaces being complementarily concave to said convex armature surface and engaged thereby when said armature is adjacent the lower end of said passage. 